In many industrial applications, solvent-based adhesives are used to laminate flat substrates. The background of this invention is the replacement of such adhesives by a film sealable on both sides.
Heatsealable polyester films in general are known and are used, for example, for packaging and industrial applications.
EP-A-0 026 006 describes an oriented sealable polyester film with an amorphous PETG sealing layer. It is produced by various lamination methods or by coextrusion of a blown film.
EP-B-1 165 317 describes a biaxially oriented sealable polyester film with an amorphous PETG sealing layer. The base layer of this film contains a high proportion of isophthalate/terephthalate, and so the film is substantially amorphous and can be deformed readily. As a result, the film, however, has a low mechanical strength, which has an adverse effect on processability particularly in the case of thin films.
WO-A-2006/121759 describes a biaxially oriented polyester film with thin sealing layers on both sides of the film. The film is particularly suitable for LAP sealing (front side to back side). Owing to the low layer thicknesses (less than 1 μm), the seal seam strength to other materials is, however, low.